1. Field of the Invention
The present invention relates a method of smelting copper.
2. Description of the Related Art
I. V. Kojo and M. Lahtinen, “Outokumpu blister smelting processes, clean technology standards”: Cu2007, The proceedings of the Carlos Diaz symposium on Pyrometallurgy, Vol. 3, Book 2, (Toronto, Canada, 2007), pp. 183-190 discloses a method using a flash converter furnace as a copper smelting method not using a P.S. converter furnace. Japanese Patent Application Publication No.2003-213347 discloses MI continuous copper smelting method as a copper smelting method not using a P.S. converter furnace.
In the method using the flash converter furnace, prepared and dried copper concentrate is charged into a flash smelting furnace, the copper concentrate is dissolved and divided into copper matte and slag, the matte is crushed and charged into the flash converter furnace after cooling, the charged matte is divided into blister and calcium ferrite slag through oxidation of the charged matte, and anode is cast by oxidizing and reducing the blister in a refining furnace.
In the MI continuous copper smelting method, prepared and dried copper concentrate is charged into a “S” furnace, the copper concentrate is dissolved and divided into copper matte and slag, the matte is charged into a “C” furnace, the charged matte is divided into blister and calcium ferrite slag through oxidation of the charged matte, and anode is cast by oxidizing and reducing the blister in a refining furnace.
The matte is collected and separated from the slag generated in the flash smelting furnace or the “S” furnace by retaining the slag in a slag cleaning furnace or a CL furnace. The separated matte is charged into the flash converter furnace or the “C” furnace. The slag is sold after water granulating. The calcium ferrite slag generated in the flash converter furnace or the “C” furnace is repeated to the flash smelting furnace or the “S” furnace and the “C” furnace after water granulating.
The calcium ferrite slag generated in the flash converter furnace or the “C” furnace includes approximately 20% of copper. The calcium ferrite slag may be used as steel raw material, if copper grade of the calcium ferrite slag is reduced.
However, the calcium ferrite slag has electrical conductivity higher than silicate slag. Therefore, it has been thought difficult to keep the dissolved calcium ferrite slag stable compared to the silicate slag, in a conventional electrical furnace using heat caused by electrical resistance. This results in repetition of the calcium ferrite slag to the flash smelting furnace or the “S” furnace and the “C” furnace after water granulating.